oncall-data-exporter: increase the timeout for stats collection
oncall-data-exporter: increase the timeout for stats collection

This should hopefully fix oncall-data-exporter (the timeouts there seem
to be due to slower RPCs rather than outright hanging RPCs).

Change-Id: I9185e5b6a0cb290087cda25cb1acf56efc88a627

vanadium/go.devtools,vanadium/go.devtools,vanadium/go.devtools